Xalitik (Category) (5e Creature)
From D&D Wiki
Variant: Alternate Fireblades
Whether through innate skill or extensive training, some xalitik can create fireblades that deal other types of damage. A variant xalitik can create a blade that deals any other type of damage, such as cold or necrotic.
A fireblade that deals a different type of damage deals the same amount of damage as an ordinary fireblade and counts as a fireblade for the purposes of triggering Flaming Rage.